Utilities for computing digests and using binary codecs in Scala

digest4s

Maven Central

A set of utilities for generating digests and handling binary codecs in Scala. Built on top of Apache Commons Codec.

Getting started

Add the following to your build.sbt file. The latest version of the library should be in the Maven badge above. Otherwise you can checkout the artefact listing on mvnrepository.com.

libraryDependencies += "au.id.tmm.digest4s" %% "digest4s-core" % "0.1.0"

The simplest way to use the library is with the syntax import:

import au.id.tmm.digest4s.syntax._

Binary codec utilities

Parsing bytes from encoded strings

import au.id.tmm.digest4s.binarycodecs.syntax._

import org.apache.commons.codec.DecoderException
import scala.collection.immutable.ArraySeq

// Parse binary encoded Strings safely

val byteArray: Either[DecoderException, ArraySeq[Byte]] = "VXQ2DXQ=".parseBase32
val byteArray: Either[DecoderException, ArraySeq[Byte]] = "reGh3g==".parseBase64
val byteArray: Either[DecoderException, ArraySeq[Byte]] = "11011110101000011110000110101101".parseBinary
val byteArray: Either[DecoderException, ArraySeq[Byte]] = "ADE1A1DE".parseHex

// Parse unsafely, throw if encoding is invalid:

val byteArray: ArraySeq[Byte] = "VXQ2DXQ=".parseBase32OrThrow
val byteArray: ArraySeq[Byte] = "reGh3g==".parseBase64OrThrow
val byteArray: ArraySeq[Byte] = "11011110101000011110000110101101".parseBinaryOrThrow
val byteArray: ArraySeq[Byte] = "ADE1A1DE".parseHexOrThrow

// Use StringContext (throws if invalid)

val byteArray: ArraySeq[Byte] = base32"VXQ2DXQ="
val byteArray: ArraySeq[Byte] = base64"reGh3g=="
val byteArray: ArraySeq[Byte] = binary"11011110101000011110000110101101"
val byteArray: ArraySeq[Byte] = hex"ADE1A1DE"

Encoding bytes into string representations

import au.id.tmm.digest4s.binarycodecs.syntax._

import scala.collection.immutable.ArraySeq

// Encode bytes to String

val bytes: Array[Byte] = Array[Byte](0xad.toByte, 0xe1.toByte, 0xa1.toByte, 0xde.toByte)

bytes.asBase32String // "VXQ2DXQ="
bytes.asBase64String // "reGh3g=="
bytes.asBinaryString // "11011110101000011110000110101101"
bytes.asHexString    // "ADE1A1DE"

// Can be used for different collection types

bytes.to(ArraySeq).asHexString // "ADE1A1DE"
bytes.toVector.asHexString     // "ADE1A1DE"
bytes.toList.asHexString       // "ADE1A1DE"

Digest utilities

Digest value classes

There are a number of value classes in the au.id.tmm.digest4s.digest package which can improve the semantic clarity of checksum fields:

import au.id.tmm.digest4s.digest._

case class Document(
  checksum: Array[Byte], // 🤷 Bad, not clear what the algorithm is
)

case class Document(
  checksum: MD5Digest,   // 😎 Clearer, describes the algorithm
)

Computing digests

import java.io.IOException

import au.id.tmm.digest4s.digest._
import au.id.tmm.digest4s.digest.syntax._

// Compute digests for safe types

val md5Digest: MD5Digest       = "Hello".md5
val sha256Digest: SHA256Digest = Array[Byte](0xad.toByte, 0xe1.toByte, 0xa1.toByte, 0xde.toByte).sha256
val sha512Digest: SHA512Digest = List[Byte](0xad.toByte, 0xe1.toByte, 0xa1.toByte, 0xde.toByte).sha512

// Compute digests for types where you might hit an IOException:

val md5Digest: Either[IOException, MD5Digest] = java.nio.file.Paths.get("test").md5OrError